Finally, the armyworm season seems to be over. Moth trapping shows that the numbers are decreasing to the lowest levels of the season. Additionally, most fields are ripening and therefore less susceptible to armyworm injury.
Overall, armyworm infestations were not as severe as last year. At the beginning of the season there were some very early infestations; however, those infestations may have been detected early because growers and PCAs were scouting closely after last year's outbreak. In most cases, the early infestations that were brought to my attention consisted of small worms, which usually go unnoticed until a few weeks later in the season.
In late August, a second infestation peak occurred. However, this infestation was similar to what we see in normal years. Nevertheless, I saw some injury that might have been approaching treatment levels.
The armyworm moth trapping conducted this year started a little later than I wanted. Next year I hope to start trapping in late May or early June so the first armyworm peak can be detected timely. Number of moths trapped remained low until August, when they started to increase and reached a peak in all locations in the Sacramento Valley. The moth peak observed in early to mid August corresponds to the increased injury observed in late August, when eggs laid by those moths reached the 3rd and 4th instars.
- Author: Whitney Brim-DeForest
The 1st Annual Rice Weed Course will take place:
Friday, September 16, 2016
from 8:30AM to 4:15PM (Registration begins at 8:00AM)
Hamilton Road Field (on West Hamilton Rd. between Hwy. 99 & Riceton Hwy.)
and Rice Experiment Station, Biggs, CA
The day will begin with an interactive tour of the Weed Science research plots at Hamilton Road. Participants will also spend time learning about weed identification for important rice weeds both at emergence and at heading. Presentations will cover emerging pests of rice, such as weedy red rice and winged-leaf primrose willow. Attendees will hear about new pesticide registrations and updates to current pesticides, as well as information regarding the new Butte herbicide. This course is also a great opportunity to interact directly with the UCCE and UC Davis Rice Weed Research Team!
For a full agenda and registration go to:
For questions, please contact Whitney Brim-DeForest at 530-822-7515, or by email at firstname.lastname@example.org
Credits for PCA, QAC, QAL, Private Applicator, and CA Certified Crop Adviser are pending.
Our two year stretch of little to no blast might be over. I visited an M-209 field last week that seemed to be infected with blast. The lesions appeared to me like propanil drift burn; however, the yellow halo around the lesions made the PCA suspicious. Paul Sanchez, pathologist at the Rice Experiment Station, collected some leaf samples and was able to confirm it is blast.
According to Paul, changes in environmental conditions may be why the lesions did not look like your typical blast lesions. When conditions are favorable, the fungus' spores germinate and infect the tissue. But if conditions change and become unfavorable for the fungus growth and sporulation, the fungus dies and the tissue then has that burned look instead of the white-gray powdery look.
Some of the lesions did look more like the typical blast lesion.
M-209 is a variety closely related to M-205, a variety considered to be susceptible to blast. Since we have not seen blast in the field since M-209 was released, we do not know what level of susceptibility M-209 has. This might be the year we find out.
At this point, a fungicide treatment is not recommended. However, a treatment near heading may be appropriate considering that the field and area have a history of blast epidemics./table>
This year, armyworm infestations were not as severe as last year. Populations did not reach the very high numbers of 2015, but they were early. Growers and PCAs were scouting diligently, and were able to recognize infestations when the worms were small. This gave growers the upper hand and many were ready to make a treatment decision if necessary. Intrepid was used in some fields successfully.
We are not totally off the hook yet. We usually get a second peak of armyworm activity during the late boot and heading stages. UCCE is monitoring moth populations in several areas of the valley using pheromone traps. The traps were set up in early July, and the trapping numbers will be shared in this blog and the UC Rice On-line website.
So far, moth numbers are low, averaging 2.5 moths/trap/day during the week of July 11. Numbers have decreased since the previous week, when the average was 4.3 moths/trap/day. The location with the highest moth numbers is near Knights Landing, averaging 9.2 moths/trap/day. Previous work done by Larry Godfrey, UC Davis Extension Entomologist, found that peaks of 20-40 moths/trap/day might indicate an armyworm larvae peak 7 to 10 days later.
Number of moths/trap/day captured in armyworm pheromone traps across the Sacramento Valley
Whitney Brim-DeForest is the newest addition to the UC Cooperative Extension Farm Advisor rice team. She will be based out of the Sutter-Yuba Office, but will serve Placer and Sacramento counties as well. She holds a Ph.D. in Horticulture and Agronomy and an M.S. in International Agricultural Development (both from UC Davis), and a double B.A. in Biology and Music from Brown University. Before starting her graduate work, she served as a Peace Corps Volunteer in Senegal, West Africa, for three years, where she worked with growers in a variety of crops, including rice, sorghum, corn, and cowpeas. Since 2012, she has worked at the Rice Experiment Station in Biggs, CA, managing the field trials for the UC Weed Science program in rice.
Why do you want to work in Cooperative Extension?
I really enjoy being out and about in the field, talking to growers and PCA's. I prefer doing research that can have an immediate impact, that results in new tools and information that growers' can use in their own fields. I find that I learn a lot from growers' and PCA's, as they are in the fields every day, and are often the best at identifying the potential implications of a research idea--the risks and benefits to growers.
What is your background?
I am a weed scientist by training, and so far, my research has been primarily focused on weed agroecology: the interaction of weeds with the rice field environment. Since I started at UC Davis, I worked first with Dr. Albert Fischer and then with Dr. Kassim Al-Khatib at the Rice Experiment Station (RES) in Biggs, where I managed the weed science field trials. During my time at the RES, through the herbicide-resistant weed testing program, I met many growers and PCA's and I am looking forward to meeting more of you!
Weed control plots at the annual Rice Field Day at the California Rice Experiment Station in Biggs, CA.
What are your research and outreach plans for the future?
This season, I plan to spend time getting to know Sutter, Yuba, Placer and Sacramento growers and PCA's, and to familiarize myself with the location of your farms, fields, and places of work. I'm looking forward to meeting as many of you as possible, so that I can begin understanding the issues that you identify as the most important.
Some of my future outreach ideas include a rice-specific workshop on weed management and identification and some videos on weed identification and seed collection. With the other farm advisors, I will be involved in research on the emerging weed issues, including red rice and the winged primrose willow. Currently, I am involved in research focusing on identifying and managing herbicide resistance, since that is a concern for many rice growers. Over the next 1 to 2 years, this will include surveying and screening for resistant populations in growers' fields.
Feel free to contact me at any time, at the Sutter-Yuba Office, at 530-822-7515, on my cell at 541-292-1553, or by email at email@example.com
Close-up of ducksalad emerging in the greenhouse/table>